CN110366083B - MEMS device and preparation method thereof - Google Patents
MEMS device and preparation method thereof Download PDFInfo
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- CN110366083B CN110366083B CN201810322117.XA CN201810322117A CN110366083B CN 110366083 B CN110366083 B CN 110366083B CN 201810322117 A CN201810322117 A CN 201810322117A CN 110366083 B CN110366083 B CN 110366083B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R19/00—Electrostatic transducers
- H04R19/005—Electrostatic transducers using semiconductor materials
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor
- H04R31/003—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor for diaphragms or their outer suspension
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2201/00—Details of transducers, loudspeakers or microphones covered by H04R1/00 but not provided for in any of its subgroups
- H04R2201/003—Mems transducers or their use
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2231/00—Details of apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor covered by H04R31/00, not provided for in its subgroups
- H04R2231/001—Moulding aspects of diaphragm or surround
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Abstract
The invention provides an MEMS device and a preparation method thereof, wherein a first insulating layer is formed on the front surface of a substrate, forming a vibrating membrane and a polar plate on the first insulating layer, forming a back cavity on the back surface of the substrate, wherein the back cavity is exposed out of the vibrating membrane and faces away from the gap, and a part of the first insulating layer is left as a support portion of the diaphragm, the diaphragm being symmetrical with respect to a projection center of the support portion on the diaphragm, and a substrate with an area opposite to the support part in the back cavity is reserved as a support substrate of the support part, when the vibrating membrane vibrates, the vibration occurs at an intermediate position between the edge and the center of the diaphragm, increasing an effective vibration area, therefore, the sensitivity and the signal-to-noise ratio of the MEMS device are improved, the vibration amplitude is reduced, and the fluctuation range of the sensitivity and the signal-to-noise ratio is reduced; while reducing the force applied to the diaphragm in the mechanical reliability test, thereby increasing the reliability of the MEMS device.
Description
Technical Field
The invention relates to the technical field of semiconductors, in particular to an MEMS (micro-electromechanical system) device and a preparation method thereof.
Background
The MEMS (Micro-Electro-Mechanical System) technology refers to a Micro System that integrates Mechanical components, driving components, optical systems, and electronic control systems into a whole, and manufactures various sensors (e.g., inertial sensor, pressure sensor, acceleration sensor, etc.), actuators, drivers, and Micro systems with excellent performance, low price, and miniaturization by using a manufacturing process that combines Micro-electronics technology and Micro-processing technology (e.g., silicon Micro-processing, silicon surface Micro-processing, wafer bonding, etc.).
The conventional MEMS device generally includes a substrate having a front surface and a back surface, the substrate having a back cavity penetrating the front surface and the back surface, a vibrating membrane formed on the front surface of the substrate, the vibrating membrane covering the back cavity, an insulating support and a plate extending over the insulating support formed on the vibrating membrane, a gap being formed between the plate and the vibrating membrane, and a plurality of through holes spaced apart from each other formed on the plate. When the MEMS device works, sound enters the gap from the through hole to cause the vibration of the vibrating membrane, and the vibrating membrane and the polar plate are opposite to form a capacitor.
However, since the diaphragm is equivalent to a thin film moving, a relatively large amplitude is generated in a relatively small effective vibration area, and the large amplitude of the vibration increases the fluctuation range of the sensitivity and the signal-to-noise ratio of the device, and in some mechanical reliability tests, a relatively large force is applied to the diaphragm, such as an air pressure test or a mechanical force impact test, which easily causes the loss or damage of the diaphragm.
Disclosure of Invention
The invention aims to provide an MEMS device and a preparation method thereof, wherein a supporting part connected with a vibrating membrane is formed in a back cavity, and a substrate with a right facing area to the supporting part in the back cavity is reserved, so that an effective vibration area is enlarged, and the sensitivity and the signal-to-noise ratio of the MEMS device are improved.
In order to achieve the above object, the present invention provides a method for manufacturing a MEMS device, comprising the steps of:
providing a substrate, wherein the substrate is provided with a front surface and a back surface;
forming a first insulating layer on the front surface of the substrate, forming a vibrating membrane and a polar plate on the first insulating layer, wherein the polar plate is positioned on the vibrating membrane and insulated and isolated from the vibrating membrane, a gap is formed between the polar plate and the vibrating membrane, and a through hole communicated with the gap is formed in the polar plate;
and forming a back cavity on the back surface of the substrate, wherein the back cavity exposes the vibrating membrane and faces away from the gap, a part of the first insulating layer is reserved as a supporting part of the vibrating membrane, the vibrating membrane is symmetrical relative to the projection center of the supporting part on the vibrating membrane, and the substrate with a right area to the supporting part is reserved in the back cavity.
Optionally, the step of forming the diaphragm includes:
forming a vibration film layer, wherein the first insulating layer is filled in the vibration film layer;
and patterning the vibration film layer to expose the edge of the first insulation layer to form a vibration film covering the first insulation layer.
Optionally, after patterning the vibration film layer, an edge of the first insulating layer is exposed.
Optionally, the step of forming the plate comprises:
forming a second insulating layer, wherein the second insulating layer covers the vibrating membrane and the first insulating layer;
patterning the second insulating layer and the first insulating layer to expose the edge of the substrate, and forming a plurality of second grooves in the second insulating layer, wherein the depth of each second groove is smaller than the thickness of the second insulating layer;
forming a polar plate material layer, wherein the polar plate material layer fills the second groove and covers the second insulating layer and the substrate;
and patterning the pole plate material layer to expose the edge of the second insulating layer to form a pole plate.
Optionally, the step of forming the through hole includes:
forming a third insulating layer, wherein the third insulating layer covers the polar plate, the second insulating layer and the substrate;
and patterning the third insulating layer and the polar plate to form a plurality of through holes exposing the second insulating layer.
Optionally, the step of forming the back cavity includes:
patterning the back surface of the substrate to form a third groove exposing the first insulating layer, wherein the third groove faces away from the gap, and part of the substrate in the third groove is reserved as a supporting substrate;
and etching part of the first insulating layer through the third groove to expose the vibrating membrane to form the back cavity, reserving part of the first insulating layer as a supporting part, and enabling the supporting part and the supporting substrate to have a dead-against area.
Optionally, the step of forming the gap includes:
and etching part of the second insulating layer through the through hole to expose the vibrating membrane, and forming a gap between the vibrating membrane and the polar plate.
Optionally, the step of etching the first insulating layer to form the back cavity and the step of etching the second insulating layer to form the gap are performed in the same process step.
Optionally, before forming the third groove, the method for manufacturing the MEMS device further includes: forming a fourth insulating layer, wherein the fourth insulating layer covers the front surface of the substrate;
removing the fourth insulating layer in the process of forming the gap.
Accordingly, the present invention also provides a MEMS device comprising:
a substrate having a front surface and a back surface;
the vibrating diaphragm is positioned on the front surface of the substrate, the polar plate is positioned above the vibrating diaphragm, the polar plate and the vibrating diaphragm are isolated in an insulating way, a gap is formed between the polar plate and the vibrating diaphragm, and a through hole communicated with the gap is formed in the polar plate;
the back cavity is positioned on the back surface of the substrate, the back cavity is exposed out of the vibrating membrane and faces away from the gap, a supporting part connected with the vibrating membrane is arranged in the back cavity, the vibrating membrane is symmetrical relative to the projection center of the supporting part on the vibrating membrane, a supporting substrate which is adjacent to the supporting part and has a right facing area is arranged in the back cavity, and the supporting substrate is connected to the substrate around the back cavity.
Optionally, the MEMS device further comprises: a first insulating layer, the first insulating layer is positioned at the edge of the substrate, and the vibrating membrane is positioned on the first insulating layer;
the second insulating layer is positioned on the edge of the vibrating membrane and the first insulating layer; and
a third insulating layer surrounding the plate, the second insulating layer and the substrate; and the through hole is positioned in the third insulating layer and communicated with the gap.
Optionally, the support portion is cylindrical, circular truncated cone or rectangular.
Optionally, the support substrate is a cuboid, and the back cavity is divided into two sub-back cavities by the support substrate.
Optionally, the support basement is the crossing structure of many cuboids, and a plurality of cuboid intersections are located the below of supporting part, the back of the body chamber quilt the support basement is separated for a plurality of sub back of the body chamber.
In the MEMS device and the preparation method thereof provided by the invention, a first insulating layer is formed on the front surface of a substrate, forming a vibrating membrane and a polar plate on the first insulating layer, forming a back cavity on the back surface of the substrate, wherein the back cavity is exposed out of the vibrating membrane and faces away from the gap, and a part of the first insulating layer is left as a support portion of the diaphragm, the diaphragm being symmetrical with respect to a projection center of the support portion on the diaphragm, and a substrate with an area opposite to the support part in the back cavity is reserved as a support substrate of the support part, when the vibrating membrane vibrates, the vibration occurs at an intermediate position between the edge and the center of the diaphragm, increasing an effective vibration area, therefore, the sensitivity and the signal-to-noise ratio of the MEMS device are improved, the vibration amplitude is reduced, and the fluctuation range of the sensitivity and the signal-to-noise ratio is reduced; while reducing the force applied to the diaphragm in the mechanical reliability test, thereby increasing the reliability of the MEMS device.
Drawings
FIG. 1 is a schematic cross-sectional view of a MEMS device.
Fig. 2 is a flowchart of a method for manufacturing a MEMS device according to an embodiment of the present invention.
Fig. 3 to 9 are schematic cross-sectional structures of steps of a method for manufacturing a MEMS device according to an embodiment of the invention.
Fig. 10 a-10 b are schematic views of the effective vibration area in a MEMS device.
FIGS. 11 a-11 b are schematic cross-sectional views of the back cavity.
Detailed Description
Fig. 1 is a schematic structural view of a MEMS device, as shown in fig. 1, the MEMS device comprising: a substrate 10, the substrate 10 having a front surface S1 and a back surface S2, a diaphragm 11 and a plate 12 formed on the front surface of the substrate 10, a support 13 formed on an edge of the substrate 10 for supporting the diaphragm 11, and the support 13 surrounding the edge of the diaphragm 11, the plate 12 being insulated from the diaphragm 11 by the support 13 with a gap 15 formed therebetween, an insulating layer 14 formed on the substrate 10, the support 13, and the plate 12, and a through hole (not identified) formed in the insulating layer 14 and the plate 12 to communicate with the gap 15; a back cavity 16 is formed on the back surface of the substrate 10, and the back cavity 16 penetrates through the substrate 10, exposes the diaphragm 11 and faces away from the gap 15.
A capacitance is formed between the diaphragm 11 and the plate 12, and sound or the like enters the gap 15 through the through hole, causing the diaphragm 11 to vibrate, i.e., move relative to the plate 12, which causes the capacitance value of the capacitance formed by the plate 12 and the diaphragm 11 to change. By measuring the change in the capacitance value relative to a reference value of capacitance when the device is stationary, the movement of the diaphragm 11 relative to the plate 12 can be measured.
Fig. 10a is a schematic diagram of the effective vibration area of the MEMS device, please refer to fig. 1 and 10a, the effective vibration area of the MEMS device is located in the central area of the back cavity 15, i.e. the O area in the figure. The effective vibration area is relatively small, the vibration film 11 generates relatively large amplitude in a relatively small effective area, the relatively large amplitude of vibration can increase the fluctuation range of the sensitivity and the signal-to-noise ratio of the MEMS device, and the force applied to the vibration film 11 during a mechanical reliability test is relatively large, so that the vibration film 11 is seriously lost or damaged, and the reliability of the MEMS device is further influenced.
In view of the above problems, the present inventors propose a method for manufacturing a MEMS device, comprising: providing a substrate, wherein the substrate is provided with a front surface and a back surface; forming a first insulating layer on the front surface of the substrate, forming a vibrating membrane and a polar plate on the first insulating layer, wherein the polar plate is positioned on the vibrating membrane and insulated and isolated from the vibrating membrane, a gap is formed between the polar plate and the vibrating membrane, and a through hole communicated with the gap is formed in the polar plate; and forming a back cavity on the back surface of the substrate, wherein the back cavity exposes the vibrating membrane and faces away from the gap, a part of the first insulating layer is reserved as a supporting part of the vibrating membrane, the vibrating membrane is symmetrical relative to the projection center of the supporting part on the vibrating membrane, and the substrate with a right area to the supporting part is reserved in the back cavity.
In the preparation method of the MEMS device provided by the invention, a first insulating layer is formed on the front surface of a substrate, forming a vibrating membrane and a polar plate on the first insulating layer, forming a back cavity on the back surface of the substrate, wherein the back cavity is exposed out of the vibrating membrane and faces away from the gap, and a part of the first insulating layer is left as a support portion of the diaphragm, the diaphragm being symmetrical with respect to a projection center of the support portion on the diaphragm, and a substrate with an area opposite to the support part in the back cavity is reserved as a support substrate of the support part, when the vibrating membrane vibrates, the vibration occurs at an intermediate position between the edge and the center of the diaphragm, increasing an effective vibration area, therefore, the sensitivity and the signal-to-noise ratio of the MEMS device are improved, the vibration amplitude is reduced, and the fluctuation range of the sensitivity and the signal-to-noise ratio is reduced; while reducing the force applied to the diaphragm in the mechanical reliability test, thereby increasing the reliability of the MEMS device.
In order to make the contents of the present invention more clearly understood, the contents of the present invention will be further described with reference to the accompanying drawings. The invention is of course not limited to this particular embodiment, and general alternatives known to those skilled in the art are also covered by the scope of the invention.
The present invention is described in detail with reference to the drawings, and for convenience of explanation, the drawings are not enlarged partially according to the general scale, and should not be construed as limiting the present invention.
The invention provides a preparation method of an MEMS device, as shown in FIG. 2, comprising the following steps:
step S100: providing a substrate, wherein the substrate is provided with a front surface and a back surface;
step S200: forming a first insulating layer on the front surface of the substrate, forming a vibrating membrane and a polar plate on the first insulating layer, wherein the polar plate is positioned on the vibrating membrane and insulated and isolated from the vibrating membrane, a gap is formed between the polar plate and the vibrating membrane, and a through hole communicated with the gap is formed in the polar plate;
step S300: and forming a back cavity on the back surface of the substrate, wherein the back cavity exposes the vibrating membrane and faces away from the gap, a part of the first insulating layer is reserved as a supporting part of the vibrating membrane, the vibrating membrane is symmetrical relative to the projection center of the supporting part on the vibrating membrane, and the substrate with a right area to the supporting part is reserved in the back cavity.
Fig. 3 to 9 are schematic structural diagrams of steps of a method for manufacturing an MEMS device according to an embodiment of the present invention, and please refer to fig. 2, which is combined with fig. 3 to 9 to describe in detail the method for manufacturing an MEMS device according to the present invention:
as shown in fig. 3, in step S100, a substrate 100 is provided, the substrate 100 having a front side S1 and a back side S2. The substrate 100 may be a silicon substrate, or a germanium, silicon germanium, gallium arsenide substrate or a silicon-on-insulator substrate. The substrate may be selected as desired by one skilled in the art, and thus the type of substrate should not limit the scope of the present invention. The substrate 100 in the present embodiment is preferably a silicon substrate. The front side S1 and the back side S2 of the substrate 100 are located at opposite sides of the substrate 100.
In step S200, a first insulating layer 110 is formed on the front surface S1 of the substrate 100, a diaphragm 120 and a plate 140 are formed on the first insulating layer 110, the plate 140 is located on the diaphragm 120 and insulated from the diaphragm 120, a gap 160 is formed between the plate 140 and the diaphragm 120, and a through hole 151 communicating with the gap 160 is formed in the plate 140, as shown in fig. 3 to 9.
In step S300, a back cavity 170 is formed on the back surface S2 of the substrate 100, the back cavity 170 exposes the diaphragm 120 and faces away from the gap 160, and a substrate having a facing area with the supporting portion 121 remains in the back cavity 170, as shown in fig. 8 and 9.
The following describes steps S200 and S300 in detail:
first, step S201 is performed, and a first insulating layer 110 is deposited on the front surface S1 of the substrate 100. Optionally, the material of the first insulating layer 110 is silicon oxide, silicon nitride, or a stack of silicon oxide and silicon nitride, or other materials known to those skilled in the art.
Then, step S202 is performed to form the diaphragm 120. Namely, the diaphragm 120 is formed on the first insulating layer 110. Referring to fig. 4, specifically, a vibration film layer is formed on the first insulating layer 110, the vibration film layer covers the first insulating layer 110, the vibration film layer is patterned to expose the edge of the first insulating layer 110, and a vibration film 120 located on the first insulating layer 110 is formed.
The diaphragm 120 is subsequently used as a diaphragm of the MEMS device, and the material of the diaphragm 120 may be polysilicon, silicon germanium, or other metal or semiconductor material with elasticity, so as to ensure that the diaphragm can recover its original shape after being vibrated and deformed by the acting force of sound or inertia force, and ensure that the diaphragm has good conductivity.
Step S203 is then performed to form the plate 140, i.e., to form the plate 140 on the diaphragm 120, resulting in the structure shown in fig. 6. Specifically, first, the second insulating layer 130 is formed on the diaphragm 120, and it should be noted that the second insulating layer 130 and the first insulating layer 110 may be made of the same material, so that the same filling method is adopted in the drawings, and no clear mark is given to an interface between the second insulating layer 130 and the second insulating layer 110 in fig. 5 and the following drawings, but the second insulating layer 130 may be made of a material different from that of the first insulating layer 110, which is not limited in the present invention.
The second insulating layer 130 covers the diaphragm 120 and the first insulating layer 110. Then, patterning the second insulating layer 130 and the first insulating layer 110, specifically, forming a patterned photoresist layer on the second insulating layer 130, etching the second insulating layer 130 and the first insulating layer 110 with the patterned photoresist layer as a mask to expose the edge of the substrate 100, and forming a plurality of second grooves 131 in the second insulating layer 130, as shown in fig. 5. The depth of the second groove 131 is smaller than the thickness of the second insulating layer 130, that is, the second groove 131 does not expose the diaphragm 120. Optionally, the second grooves 131 are uniformly distributed on the second insulating layer 130, and the second grooves 131 correspond to the vibration film 120.
Next, a plate material layer is formed, and the plate material layer fills the second recess 131 and covers the second insulating layer 130 and the substrate 100. Finally, patterning the plate material layer, that is, forming a patterned photoresist layer on the plate material layer, etching the plate material layer by using the patterned photoresist layer as a mask to expose the edge of the second insulating layer 130, thereby forming a plate 140, as shown in fig. 6. The material of the plate 140 may be selected from polysilicon, silicon germanium, or germanium, and may also be other metals such as aluminum, or other materials known to those skilled in the art.
Step S204 is performed to form a through hole, i.e., to form a through hole 151 on the plate 140, as shown in fig. 7. Specifically, first, a third insulating layer 150 is formed, and the third insulating layer 150 covers the plate 140, the second insulating layer 130, and the substrate 100; then, the third insulating layer 150 and the plate 140 are patterned to form a plurality of through holes 151 exposing the second insulating layer 130. For example, a patterned photoresist layer is formed on the third insulating layer 150 to expose a position of a through hole to be formed on the third insulating layer, and then the third insulating layer 150 and the plate 140 are etched using the patterned photoresist layer as a mask until the second insulating layer 130 is exposed, so that a plurality of through holes 151 are formed in the third insulating layer 150 and the plate 140.
Next, optionally, a fourth insulating layer (not shown) is formed on the front surface S1 of the substrate 100, and the fourth insulating layer fills the through hole 151 and covers the third insulating layer 150 and the substrate 100, i.e., the fourth insulating layer covers the front surface S1 of the substrate 100. The influence on the structure of the front surface of the substrate 100 when the back surface of the substrate 100 is subsequently operated is avoided. The material of the fourth insulating layer is preferably silicon oxide, silicon nitride or a stacked structure of silicon oxide/silicon nitride, or other materials known to those skilled in the art.
Step S301 is then performed to form a third recess, i.e., a third recess 101 is formed on the back side S2 of the substrate 100, as shown in fig. 8. Specifically, the back surface S2 of the substrate 100 is patterned to form a third groove 101 exposing the first insulating layer 110, the third groove 101 faces away from a gap to be formed, and a part of the substrate in the third groove 101 is reserved as a supporting substrate 102 for supporting a subsequently formed supporting portion, where the supporting substrate 102 and the subsequently formed supporting portion have a facing area.
Then, step S205 and step S302 are performed simultaneously to form a gap and a back cavity, that is, a gap 160 is formed between the plate 140 and the diaphragm 120, and a back cavity 170 is formed in the third groove 101, so as to form the structure shown in fig. 9.
Specifically, a BOE (Buffered Oxide Etch) method is adopted, the structure formed in the previous step is placed in an Oxide etching solution, the etching solution etches the first insulating layer 110 through the third groove 101 until the vibrating membrane 120 is exposed, and a back cavity 170 is formed on the back surface of the substrate 100. In the process of etching the first insulating layer 110 with the etching solution, the etching solution simultaneously etches the fourth insulating layer, and after the fourth insulating layer is removed, the second insulating layer 130 is etched through the through hole 151, a part of the second insulating layer 130 is removed, and a gap 160 between the vibrating membrane 120 and the pole plate 140 is formed. That is, the removal of the fourth insulating layer, the formation of the gap 160, and the formation of the back cavity 170 are performed in the same process step (i.e., BOE).
Of course, in other embodiments, the removal of the fourth insulating layer, the formation of the gap 160 and the formation of the back cavity 170 may not be performed in the same step, and the invention is not limited thereto.
Since a part of the substrate remains in the first groove 101 as the supporting substrate 102, when the first insulating layer 110 is etched through the first groove 101, the supporting substrate 102 can protect a corresponding part of the first insulating layer from being etched, so as to form the supporting layer 112. The diaphragm 120 is symmetrical with respect to the projection center of the support structure 112 on the diaphragm 120, i.e. the diaphragm 120 is a central symmetrical pattern, and the symmetry center is the projection of the support structure 112 on the diaphragm 120, i.e. the support structure 112 is located below the center of the diaphragm 120. The position and shape of the support structure 112 are controlled by the shape, position, or BOE etch conditions of the support substrate 101.
In the present embodiment, the supporting structure 121 preferably has a cylindrical shape, a circular truncated cone shape, a rectangular parallelepiped shape, or other structures known to those skilled in the art. In other embodiments, the number of support structures may also be two, three or more. The structure and number of the supporting structures 112 are not limited in the present invention.
In the method for manufacturing the MEMS device, a first insulating layer 110 is formed on a front surface S1 of a substrate 100, a diaphragm 120 and a plate 140 are formed on the first insulating layer 110, a back cavity 170 is formed on a back surface S2 of the substrate 100, the back cavity 170 exposes the diaphragm 120 and faces away from the gap 160, and a portion of the first insulating layer 110 is reserved as a supporting portion 112 of the diaphragm 120, the diaphragm 120 is symmetrical with respect to a projection center of the supporting portion 112 on the diaphragm 120, and a substrate with a right area to the supporting portion 112 in the back cavity 170 is reserved as a supporting substrate 102 of the supporting portion 121. Compared with fig. 1 and 10a, the area with relatively large amplitude in the center of the original back cavity 15 is shifted to the periphery, and as shown in fig. 10a and 10b, the area with relatively large amplitude is shifted from the O area to the AB area, so that the effective vibration area is increased, and the vibration amplitude is reduced. Of course, the amplitudes in the AB region or the O region are not the same, and the regions marked in fig. 10a and 10b only represent that the amplitude in this region is larger than the amplitudes in the other regions.
In the preparation method of the MEMS device, the effective vibration area is increased and the vibration amplitude is reduced through the supporting part 112 and the supporting substrate 102 positioned at the bottom of the supporting part 112, so that the sensitivity and the signal-to-noise ratio of the MEMS device are improved, and the fluctuation range of the sensitivity and the signal-to-noise ratio is reduced; while reducing the force applied to the diaphragm 120 in the mechanical reliability test, thereby increasing the reliability of the MEMS device.
Correspondingly, the invention also provides an MEMS device which is prepared by adopting the preparation method of the MEMS device. As shown in fig. 9, the present invention provides a MEMS device, comprising:
a substrate 100 having a front side S1 and a back side S2;
a diaphragm 120 located on the front surface S1 of the substrate 100, a plate 140 located above the diaphragm 120, the plate 140 being insulated from the diaphragm 120 and having a gap 160 formed therebetween, and a through hole 151 formed in the plate 140 and communicating with the gap 160;
a back cavity 170 located at the back surface S2 of the substrate 100, the back cavity 170 exposing the diaphragm 120 and facing away from the gap 160, and a support part 112 connected to the diaphragm 120 is disposed in the back cavity 170, the diaphragm 120 is symmetrical with respect to a projection center of the support part 112 on the diaphragm 120, a support substrate 102 having a facing area with the support part 112 is disposed in the back cavity 170, and the support substrate 102 is connected to the substrate 100 around the back cavity 170.
Optionally, the MEMS device further comprises:
a first insulating layer 110, wherein the first insulating layer 110 is located at an edge of the substrate 100, and the diaphragm 120 is located on the first insulating layer 110;
a second insulating layer 130, wherein the second insulating layer 130 is located on the diaphragm 120 and the first insulating layer 110; and
a third insulating layer 150, wherein the third insulating layer 150 surrounds the plate 140, the second insulating layer 130 and the substrate 100; the through hole 151 is located in the third insulating layer 150 and communicates with the gap 160.
Alternatively, in the present embodiment, the supporting portion 112 has a cylindrical shape, a circular truncated cone shape, a rectangular parallelepiped shape, or other shapes known to those skilled in the art. The back cavity 170 is cylindrical, the support substrate 102 is located in the back cavity 170, as shown in fig. 11a, the support substrate 102 is rectangular, that is, the cross section of the support substrate 102 is rectangular, the back cavity 170 is divided into two sub back cavities by the support substrate 102, that is, the support substrate 102 is a single substrate, and of course, the support substrate 102 may also be in other shapes except for the rectangular parallelepiped.
As shown in fig. 11b, the support substrate 102 is a structure in which a plurality of cuboids intersect, a plurality of cuboid intersection points are located below the support portion, the back cavity 170 is divided into a plurality of sub back cavities by the support substrate 102, and the position of the substrate 100 is also shown in fig. 11b, so as to determine the positional relationship between the substrate 100 and the support substrate 102, but the substrate 100 is not limited to the square shown in the figure. The shape and number of the supporting portion 121 and the supporting substrate 102 are not limited in the present invention.
In summary, in the MEMS device and the method for fabricating the same according to the present invention, the first insulating layer is formed on the front surface of the substrate, forming a vibrating membrane and a polar plate on the first insulating layer, forming a back cavity on the back surface of the substrate, wherein the back cavity is exposed out of the vibrating membrane and faces away from the gap, and a part of the first insulating layer is left as a support portion of the diaphragm, the diaphragm being symmetrical with respect to a projection center of the support portion on the diaphragm, and a substrate with an area opposite to the support part in the back cavity is reserved as a support substrate of the support part, when the vibrating membrane vibrates, the vibration occurs at an intermediate position between the edge and the center of the diaphragm, increasing an effective vibration area, therefore, the sensitivity and the signal-to-noise ratio of the MEMS device are improved, the vibration amplitude is reduced, and the fluctuation range of the sensitivity and the signal-to-noise ratio is reduced; while reducing the force applied to the diaphragm in the mechanical reliability test, thereby increasing the reliability of the MEMS device.
The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.
Claims (13)
1. A preparation method of a MEMS device is characterized by comprising the following steps:
providing a substrate, wherein the substrate is provided with a front surface and a back surface;
forming a first insulating layer on the front surface of the substrate, forming a vibrating membrane and a polar plate on the first insulating layer, wherein the polar plate is positioned on the vibrating membrane and insulated and isolated from the vibrating membrane, a gap is formed between the polar plate and the vibrating membrane, and a through hole communicated with the gap is formed in the polar plate;
and forming a back cavity on the back surface of the substrate, wherein the back cavity exposes the vibrating membrane and faces away from the gap, and a part of the first insulating layer is reserved as a supporting part of the vibrating membrane, the vibrating membrane is symmetrical relative to the projection center of the supporting part on the vibrating membrane, the edge of the vibrating membrane is fixed on the first insulating layer around the back cavity, and the substrate with a right area to the supporting part is reserved in the back cavity.
2. The method of manufacturing a MEMS device according to claim 1, wherein the step of forming the diaphragm includes:
forming a vibration film layer, wherein the vibration film layer covers the first insulating layer;
and patterning the vibration film layer to expose the edge of the first insulation layer to form a vibration film covering the first insulation layer.
3. The method of fabricating a MEMS device of claim 2, wherein the step of forming the plate comprises:
forming a second insulating layer, wherein the second insulating layer covers the vibrating membrane and the first insulating layer;
patterning the second insulating layer and the first insulating layer to expose the edge of the substrate, and forming a plurality of second grooves in the second insulating layer, wherein the depth of each second groove is smaller than the thickness of the second insulating layer;
forming a polar plate material layer, wherein the polar plate material layer fills the second groove and covers the second insulating layer and the substrate;
and patterning the pole plate material layer to expose the edge of the second insulating layer to form a pole plate.
4. The method of fabricating a MEMS device of claim 3, wherein the step of forming the via hole comprises:
forming a third insulating layer, wherein the third insulating layer covers the polar plate, the second insulating layer and the substrate;
and patterning the third insulating layer and the polar plate to form a plurality of through holes exposing the second insulating layer.
5. The method of fabricating a MEMS device of claim 4, wherein the step of forming the back cavity comprises:
patterning the back surface of the substrate to form a third groove exposing the first insulating layer, wherein the third groove faces away from the gap, and part of the substrate in the third groove is reserved as a supporting substrate;
and etching part of the first insulating layer through the third groove to expose the vibrating membrane to form the back cavity, reserving part of the first insulating layer as a supporting part, and enabling the supporting part and the supporting substrate to have a dead-against area.
6. The method of fabricating a MEMS device of claim 5, wherein the step of forming the gap comprises:
and etching part of the second insulating layer through the through hole to expose the vibrating membrane, and forming a gap between the vibrating membrane and the polar plate.
7. The method for manufacturing an MEMS device according to claim 6, wherein the step of etching the first insulating layer to form the back cavity and the step of etching the second insulating layer to form the gap are performed in the same process step.
8. The method of fabricating a MEMS device according to claim 6, wherein before forming the third recess, the method of fabricating a MEMS device further comprises: forming a fourth insulating layer, wherein the fourth insulating layer covers the front surface of the substrate;
removing the fourth insulating layer in the process of forming the gap.
9. A MEMS device, comprising:
a substrate having a front surface and a back surface;
the vibrating diaphragm is positioned on the front surface of the substrate, the polar plate is positioned above the vibrating diaphragm, the polar plate and the vibrating diaphragm are isolated in an insulating way, a gap is formed between the polar plate and the vibrating diaphragm, and a through hole communicated with the gap is formed in the polar plate;
the back cavity is positioned on the back surface of the substrate, the back cavity is exposed out of the vibrating membrane and faces away from the gap, a supporting part connected with the vibrating membrane is arranged in the back cavity, the vibrating membrane is symmetrical relative to the projection center of the supporting part on the vibrating membrane, a supporting substrate which is connected with the supporting part and has a right facing area is arranged in the back cavity, and the supporting substrate is connected to the substrate around the back cavity;
and the first insulating layer is positioned between the vibrating membrane and the substrate, and the edge of the vibrating membrane is fixed on the first insulating layer around the back cavity.
10. The MEMS device of claim 9, further comprising: a first insulating layer, the first insulating layer is positioned at the edge of the substrate, and the vibrating membrane is positioned on the first insulating layer;
the second insulating layer is positioned on the edge of the vibrating membrane and the first insulating layer; and
a third insulating layer surrounding the plate, the second insulating layer and the substrate; and the through hole is positioned in the third insulating layer and communicated with the gap.
11. The MEMS device of claim 9, wherein the support portion has a cylindrical shape, a truncated cone shape, or a rectangular parallelepiped shape.
12. The MEMS device of claim 9, wherein the support substrate is a cuboid, and the back cavity is divided by the support substrate into two sub-back cavities.
13. The MEMS device of claim 9, wherein the support substrate is a structure in which a plurality of cuboids intersect, a plurality of cuboid intersections are located below the support portion, and the back cavity is divided into a plurality of sub-back cavities by the support substrate.
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| WO2012012939A1 (en) * | 2010-07-28 | 2012-02-02 | Goertek Inc. | Cmos compatible mems microphone and method for manufacturing the same |
| KR20120061422A (en) * | 2010-12-03 | 2012-06-13 | 한국전자통신연구원 | Mems microphone |
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| CN103347808B (en) * | 2011-12-29 | 2016-02-10 | 歌尔声学股份有限公司 | Silica-based MEMS microphone, the system comprising this microphone and encapsulation |
| CN103402163B (en) * | 2013-07-26 | 2016-06-15 | 歌尔声学股份有限公司 | Shock resistance silicon base MEMS microphone and manufacture method thereof |
| CN203368755U (en) * | 2013-07-26 | 2013-12-25 | 歌尔声学股份有限公司 | Impact resistant silicon substrate MEMS microphone |
| CN204231667U (en) * | 2014-11-19 | 2015-03-25 | 北京卓锐微技术有限公司 | A kind of silicon capacitor microphone |
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| CN104848982B (en) * | 2015-05-29 | 2018-01-19 | 歌尔股份有限公司 | Quasi- differential capacitance type MEMS pressure sensor and its manufacture method |
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